SOLUTION: The amount, A, of 80 grams of a certain radioactive material remaining after t years can be found by the equation A = 80(0.613)t At what time will 40 grams remain? Please round yo

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: The amount, A, of 80 grams of a certain radioactive material remaining after t years can be found by the equation A = 80(0.613)t At what time will 40 grams remain? Please round yo      Log On


   

Question 451664: The amount, A, of 80 grams of a certain radioactive material remaining after t years can be found by the equation A = 80(0.613)t At what time will 40 grams remain? Please round your answer to two decimal places.
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!




We want A to be 40, so:



Take the log of both sides (I use ln, but base doesn't matter)



Use the properties of logarithms:



And solve:



You can do your own arithmetic and rounding.

John

My calculator said it, I believe it, that settles it
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